diff --git a/testing/web-platform/meta/MANIFEST.json b/testing/web-platform/meta/MANIFEST.json
index 3546e7ce83eea..273ad55765dcb 100644
--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -597968,7 +597968,7 @@
    "testharness"
   ],
   "html/rendering/non-replaced-elements/the-fieldset-element-0/legend-dynamic-update.html": [
-   "8b49afdceb485614cba5b2da48b155618c6fedbf",
+   "5dc68244fe0f896388ce7a0ff9d8f49397395078",
    "support"
   ],
   "html/rendering/non-replaced-elements/the-fieldset-element-0/legend-float-abspos.html": [
diff --git a/testing/web-platform/tests/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-dynamic-update.html b/testing/web-platform/tests/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-dynamic-update.html
index 8b49afdceb485..5dc68244fe0f8 100644
--- a/testing/web-platform/tests/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-dynamic-update.html
+++ b/testing/web-platform/tests/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-dynamic-update.html
@@ -1,4 +1,5 @@
 <!DOCTYPE html>
+<html class=reftest-wait>
 <title>legend and dynamic update</title>
 <link rel=fieldset-foo-ref.html>
 <p>There should be a normal fieldset below with the legend "Foo".</p>
@@ -6,5 +7,13 @@
   <legend>F</legend>
 </fieldset>
 <script>
-  document.querySelector('legend').textContent += "oo";
+  const legend = document.querySelector('legend');
+  // force layout
+  legend.offsetTop;
+  requestAnimationFrame(() => {
+    legend.textContent += "oo";
+    requestAnimationFrame(() => {
+      document.documentElement.removeAttribute('class');
+    });
+  });
 </script>
